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  • American Society of Hematology  (2)
  • 1
    In: Blood, American Society of Hematology, Vol. 114, No. 22 ( 2009-11-20), p. 2153-2153
    Abstract: Abstract 2153 Poster Board II-130 Hematopoietic progenitor and stem cells (HSC) reside in the bone marrow and have to be mobilized into the circulation prior to being collected by apheresis. The number of apheresis procedures needed and the success of transplantation are determined by the efficiency of stem cell mobilization. Between January 2004 to December 2008, 840 patients (pt) with the following diagnoses were scheduled to undergo leukapheresis for autologous transplantations: multiple myeloma (MM, n=602) and non-Hodgkin's lymphoma (NHL, n=238). Mobilization data and transplantation outcome were analyzed retrospectively. Most of the pt mobilized readily: close to 85% of the pt had a level of 20/μL to 〉 500/μL of CD34+ cells at the peak of stimulation. Of the 840 pt, 129 (15.3%) were considered to be “Poor Mobilizers” (PM), defined as pt who had a peak concentration of 〈 20/μL of CD34+ cells upon stimulation with G-CSF subsequent to induction chemotherapy appropriate for the respective disease. Among them, 38 (4.5%) pt had CD34+ levels of between 11-19/μL at maximum stimulation, defined as borderline PM, 49 (5.8%) pt had CD34+ levels of between 6-10/μL, defined as relative PM and 42 pt (5%) with levels of 〈 5/μL, defined as absolute PM. We have analyzed the relationship between poor mobilizations with types of disease (MM versus NHL), sex, age, body weight, previous irradiation, number of cycles of previous combination chemotherapy, and pretreatment with melphalan. There was no difference in the incidence of PM between pt with MM versus those with NHL. Sex, age, body weight and previous irradiation therapy did not make any significant difference. Only the number of cycles of previous chemotherapy (p=0.0034), and previous treatment with melphalan (p=0.0078) had a significant impact on the ability to mobilize. Secondary strategies to mobilize HSC from the 33 who failed included: (1) Administration of another cycle of induction chemotherapy + G-CSF. The goal of harvesting 2.0 × 10exp6 CD34+ cells/kg body weight could be accomplished in 7 of 21 of these patients. (2) G-CSF alone for 4 days (up to 8 days of stimulation) after hematopoietic recovery from previous induction chemotherapy. The goal could be achieved in 2 of the 9 patients thus mobilized. (3) Plerixafor within the compassionate use program. The goal was accomplished in 7 of 8 patients within one cycle of mobilization. All 8 could be transplanted successfully. (4) Bone marrow harvest in lieu of collection of peripheral HSC in 5 patients. For the good mobilizers, the median time to recovery of the WBC to 1.0/nL or granulocyte of 0.5/nL (whichever is sooner) was 13 days with a range of 7 to 22 days, whereas for the PM group it was 14 days with a range of 8 to 37 days. This difference was statistically not significant. The median time to recovery of the platelets counts to an unmaintained level of 〉 20/nL was 11 days with a range of 6 to 17 days for the good mobilizers, whereas for the PM it was 11 days with a range of 7 to 32 days. Again this difference was statistically not significant. The majority of the patients nowadays intended for autologous transplantations were able to mobilize readily. According to the criteria proposed in this study, 15.3% were considered to be “Poor Mobilizers”, 4.5% borderline PM, 5.8% relative PM and 5% absolute PM. No significant difference was found between patients with NHL versus MM. Sex, age, body weight and previous irradiation therapy did not make any difference. Only the number of cycles of previous chemotherapy (p=0.0034), and previous treatment with melphalan (p=0.0078) had a significant impact. Above all, as long as 2.0 × 10exp6 of CD34+ cells per kg of body weight have been collected, poor mobilization was not associated with inferior engraftment. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2009
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    In: Blood, American Society of Hematology, Vol. 112, No. 11 ( 2008-11-16), p. 1345-1345
    Abstract: INTRODUCTION: Normal hematopoietic stem cells (HSC) are characterized by their ability to self-renew, to generate multiple cell-lineages, and show slow divisional kinetics. Leukemic stem cells (LSC) have been reported to show similar characteristics but their identification has been elusive. We have studied various methods and have identified aldehyde dehydrogenase (ALDH) staining as an optimal method for the enrichment of primary human LSC. MATERIAL & METHODS: Bone marrow samples were obtained from patients with newly diagnosed AML after informed consent. Mononuclear cells were stained with Aldefluor and sorted by flow cytometry according to their forward/side scatter characteristics and ALDH activity (ALDH+/ALDH−). Alternatively, primary AML samples were being enriched for CD34+ cells by magnetic column, then double-stained with CD34-antibodies and Aldefluor and sorted for the co-expression of CD34+ and ALDH+, respectively for CD34+ alone. Human Mesenchymal Stromal Cells (MSC), isolated from human bone marrow, were used as a surrogate model for the cellular microenvironment of the hematopoietic niche. Adhesion of various AML cell lines and subpopulations of primary leukemic cells (ALDH+, ALDH−, CD34+, CD34+/ALDH+, all blasts) to MSC was tested in the adhesion chamber assay. Semi-quantitative RT-PCR was used to analyze the gene expression of various adhesion molecules and Western- Blot analysis was performed to validate the PCR-results on protein level. The generation of secondary leukemic colonies was evaluated in a semi-solid methylcellulose medium, as well as in a long term co-culture system (LSC-IC assay; in analogy to the LTC-IC assay). RESULTS: The percentage of ALDH+ cells ranged from 0.01% to 13.2% with a median of 1.47% (n=55). Adhesion significantly differed in the ALDH+ and ALDH− subpopulations: 85±4% of ALDH+ cells but only 61±8% of ALDH− cells were adherent (n=11, p & lt;0.001). Adhesion molecules, such as CXCR4 and CD44, were highly expressed on the ALDH+ subpopulation both on mRNA level and protein level, in contrast to the ALDH− subpopulation. Analysis of the initial divisional kinetics on single cell base showed that the ALDH+ subpopulation contained more slow dividing cells whereas the majority of the ALDH− subpopulation consisted of fast-dividing cells (n=3; p & lt;0.01). The frequency of long term leukemic colony initiating cells (LSC-IC) was 3.82% in the ALDH+ but only 0.01% in the ALDH− (n=21; p & lt;0.01). In the CD34+ the LSC-IC frequency was 1.96% versus 0.01% in the CD34− (n=5, p & lt;0.01). The highest LSC-IC frequency could be monitored in ALDH+/CD34+ cells: 6.1% generated secondary leukemic colonies (n=5). These colonies, harvested after 7 weeks of cultivation, were examined for their immune phenotype and screened for cytogenetic aberrations by fluorescent in situ hybridization (FISH) and the chromosomal aberrations were consistent with the AML samples taken at diagnosis. Furthermore, the frequency of ALDH+ cells correlated significantly with adverse prognostic factors: patients with a high-risk karyotype had a mean of 2.9% ALDH+ cells (n=21); in contrast, patients with a normal karyotype had a mean of 0.4% ALDH+ cells in their bone marrow (n=34; p & lt;0.001). The ability of ALDH+ versus ALDH− subsets to generate secondary leukemia in the animal model is concurrently examined. DISCUSSION: In summary, measurement of the ALDH activity provides a useful tool for the isolation of a distinct AML-blast subpopulation with stem-cell like features (LSC). The ALDH+ subsets showed higher affinity to the surrogate niche (MSC), elevated expression of CD44, Cadherin-2, and CXCR4 and were associated with an increased frequency of secondary leukemic colonies in vitro (LSC-IC). Above all, the frequency of ALDH+ blasts correlated with clinical prognostic factors, which substanciates LSC as a relevant therapeutic target.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
    RVK:
    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2008
    detail.hit.zdb_id: 1468538-3
    detail.hit.zdb_id: 80069-7
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
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